Abstract: A nested cup dipole feed capable of collinear polarization for all bands, and frequency staggering of one linear polarization with respect to the orthogonal linear polarization. The dipole elements for all bands are collinearly placed, making one linearly polarized set to be orthogonal to the other collinear sets. One collinearly placed dipole can be tuned differently from the orthogonal ones to permit frequency staggering at the crossover frequencies, thus permitting at least high gain for one polarization.

Abstract: A TE.sub.21 coupler having at least two auxiliary rectangular waveguides asymmetrically disposed around the center line of a TE.sub.21 circular waveguide, the waveguides sharing common walls in which coupling slots are disposed, the slots providing for rectangular TE.sub.10 mode propagation coupling to orthogonally aligned TE.sub.21 modes in the circular waveguide.

Abstract: A fiber optic corporate power divider/combiner for use in fiber optic systems is provided. When functioning as an optical divider, the invention includes a dielectric lens for converting incoming optical energy from a divergent spherical wave to a plane wave. A micro-lens array in optical alignment with the dielectric lens functions to partition and focus the plane wave to provide a coherent phase optical dot pattern. A fiber bundle is provided to receive and uniformly distribute the coherent phase optical dot pattern. When functioning as an optical combiner, the invention includes the micro-lens array to convert an incoming coherent phase optical dot pattern from a plurality of divergent spherical waves to a plane wave. The dielectric lens optically aligned with the micro-lens array receives and converts the plane wave to a convergent spherical wave and a single optical fiber receives and transforms the convergent spherical wave into parallel rays for transmission.

Abstract: An adaptive polarization combining system automatically adjusts the polarization of a polarization diverse antenna to match that of the incoming RF signal, thereby maximizing the received signal-to-noise ratio. Signals from the orthogonally polarized ports of the antenna are passed through a variable combiner circuit which is adjusted to maximize the combined signal at a single output port. Sample signals from each antenna port are provided to a calibration circuit which obtains phase and amplitude information from the two orthogonally polarized received signals and uses this information to control the combiner circuit phase shifters to adapt the combiner circuit to the polarization of the received signals. Therefore, the combining system can rapidly adapt electronically to polarization changes in the received signals.

Abstract: An improved angle of arrival measurement technique for monopulse antenna systems employing phase shifters on each of the four feeds to resolve ambiguities and to increase the beam splitting (angle of arrival) accuracy. To resolve ambiguities, the phase shifters are employed to shift or steer the sum and difference beams a predetermined angular amount relative to a signal of interest, and the resulting change in the angle of arrival of the returned signal is noted. The position of the original signal, as displayed on an output device, such as a radar display, for example, is then compared with the position of the signal received with respect to the shifted beam. This comparison reveals whether a true signal has been received or not. If the signal of interest is intercepted in the main beam, then the position thereof after the beam has been steered remains in the main lobe of the beam, and hence the signal of interest remains detected.

Abstract: A rotating reflector is used to provide a beam scan throughout a predetermined angle such as 360.degree.. A circular polarizer is coupled with the reflector and converts received linearly polarized energy into circularly polarized energy. A fixed feed is configured to receive the reflected circularly polarized energy and converts such energy to linearly polarized energy. The antenna system can receive the same linear polarization of energy throughout its 360.degree. scan angle without polarization mismatch or orthogonal polarization losses. The relative orientation of the two polarizers may be adjusted to receive any orientation of linear polarization of energy throughout the scan angle. For example, they may be oriented so that the antenna system receives vertically polarized energy, slant 45.degree. linearly polarized energy, or horizontally polarized energy.

Abstract: A low profile, mechanical scan antenna having an aperture assembly and a travel guide assembly is disclosed. The aperture assembly is mounted on a carriage for movement along the travel guide assembly which is rotatably mounted for rotation about an azimuth axis. The travel guide assembly includes an arcuately shaped track and the aperture assembly and carriage move along the inside of the arcuately shaped track through the scanning angle. The arcuately shaped track defines an effective antenna gimbal axis which is in front of the antenna aperture.

Abstract: Disclosed is a power divider/combiner using two parallel plate radial transmission lines having parallel plate spacing of less than .lambda./2 and which operates in a higher order mode, preferably the first higher order circumferential mode TE.sub.11. High isolation between amplifiers coupled to the radial transmission lines at their circumferences is achieved by coupling an arrangement of circulators between the amplifiers and the radial transmission lines. This isolation arrangement reduces the effects of any spurious signals that are generated by means such as imperfections and imbalances in any active devices coupled to the radial line and permits de-energizing amplifiers as desired for lowering power output without degrading performance.

Abstract: A single channel antenna tracking system for frequency-hopping communication systems. The tracking system utilizes the synchronization pulses accompanying the frequency-hopping data bursts. The receive antenna system includes an antenna feed network for providing sum and difference antenna receive signals. The tracking system comprises a tracking switch circuit which normally switches the antenna system sum signal to the receiver during reception of a frequency-hopping data burst. During the reception of an agile synchronization pulse, however, the switching system is adapted to timeshare between the antenna sum signal and the difference signal or signals. During the synchronization pulse duration, the receiver thus receives a single waveform which during one portion of the sync pulse represents the sum signal and during one or two other portions represents the difference signals. The respective sum and difference signals may then be processed to determine the antenna tracking error.

Abstract: A cylindrical cavity-backed multipole antenna system for high frequency applications is disclosed. The antenna system comprises a plurality N of planar radiation elements disposed on a dielectric disc mounted on the top surface of a conductive cylindrical cavity and equally spaced about its axis. A network circuit is adapted to introduce, for the system sum signal, progressive phase shifts of 360.degree./N to signals associated with adjacent elements and, for the difference signal, progressive phase shifts of 720.degree./N. The antenna system may be used to both transmit and receive electromagnetic radiation. The antenna sum and difference patterns are substantially symmetric in space about the antenna boresight.

Abstract: A lightweight microwave filter device is disclosed which utilizes a housing made of a lightweight metal such as aluminum having a relatively large coefficient of thermal expansion. The microwave filter also utilizes resonator elements which are either interdigital or in a comb-line filter arrangement. The resonator rods are made in two segments -- a lightweight metal such as aluminum having a relatively large coefficient of thermal expansion and a metal having a very low coefficient of thermal expansion such as invar. As the temperature varies the length of the rod also varies. The tuning capacitance between the rods and the housing varies with temperature changes and compensates for the change in the rod length. Thus the resonant frequency of the microwave filter is maintained relatively constant over a predetermined temperature range.

Abstract: An antenna feed system having a very wide (multi-octave) bandwidth. The antenna feed comprises a plurality of nested annular cavities each parasitically excited by a pair of orthogonal two-point fed dipoles. The frequency selective properties of the dipoles and the annular cavities in conjunction with the focal distribution of the reflector or lens with which the feed is used results in a multiplexing of sub-bands across the total bandwidth. A modification of the end members of the two-point fed dipoles permits dual-plane and dual polarization monopulse operation of the feed system.

Abstract: A microwave tuning device is disclosed which utilizes a resonator rod mounted in a housing. One end of the resonator rod is attached, or shorted, to the housing wall and the other end is unattached or open. The open end of the resonator rod has a cylindrical recess and an insulator ring is disposed between the open end of the resonator rod and the cavity wall. A tuning screw is incrementally inserted through the insulator ring and into the cylindrical recess for adjusting the tuning capacitance and thereby the resonant frequency.

Abstract: A small wavelength antenna comprises a paraboloidal reflector with a rim about its periphery and a single feed dipole, backed by a circular cup-shaped cavity. The reflector, dipole and cavity are symmetrically aligned about the antenna axis. The reflector diameter is on the order of 3 to 4.lambda. and the cavity diameter is less than 1.lambda. and more than 1/2.lambda., where .lambda. is any wavelength with the band of operation of the antenna. The cavity depth is on the order of 0.25 of a selected wavelength within the band, at which maximum pattern symmetry is desired, and the dipole is substantially flush with the open end of the cavity. The rim height is on the order of one-half of a selected wavelength within the band of operation of the antenna at which gain is to be optimized.